It would be a good idea to keep you eyes and ears alert to severe thunderstorm and flood potential during the next 48 hours. A storm unique in its structure, track, incorporation of deep tropical moisture and powerful upper dynamics will spell big trouble for most of the state through Wednesday night. Rainbands should organize over the Rio Grande Valley and Gulf Coast, expand, intensify and lurch northward during Tuesday. Since the powerful, compact upper low will be forced to recurve north-northeast from Mexico, convection will explode across western and central sections of the state. This precipitation will soon merge with the heavy rain along the surface warm front, which should be close to a US 84 line by Wednesday morning.
When I made this forecast, I had to "up the ante" about severe weather potential through the southern half of the Lone Star State. With the low and surface warm front moving a bit farther north than was earlier predicted, instability issues will crop up to the right of the path of the surface low. The vorticity, shear, and helicity environments, when viewed with against lifted indices between 0 and -5 could allow for a rogue tornado or two in Texas below Interstate 20. The more likely severe thunderstorm outcomes are strong winds and hail, which will not exit the state into Louisiana and Arkansas until early Thursday morning.
But of course the big deal about this feature will be the rain. Incredibly high precipitable water counts in the atmosphere, matched with equally astounding vertical velocities, could bring anywhere between 3 and 9 inches of rain to Texans living outside of the Panhandle and New Mexico border counties. Computer models have been extremely consistent on this topic, and bring the worst of the heavy rains to the Houston metro later Tuesday night and on Wednesday.
There should be some brief "recovery" of sorts on Thursday as the disturbance weakens and moves toward the Ohio Valley. But lest you get too used to nice and calm conditions, check out the satellite views from Hawaii into the Aleutian Islands. Another larger and stronger low, this one with a boost of energy from the equatorial regions, will be digging into California and then toward New Mexico. Arriving in the High Plains on Friday, a new coastal warm front will set up over southeastern Texas, resulting in fog, drizzle and a few showers. Heavy to severe thunderstorms will again appear on Saturday into Sunday, but this time with a different twist: much colder air will follow accompanied by gusty north winds. That chill you experience on Sunday afternoon and night may well linger through the next weekend!
Tuesday: Cloudy, breezy and mild with periods of rain. Heavy rain and thunderstorms likely in the later afternoon. Highs 66 Tomball to 70 Texas City
Tuesday Night: Periods of rain and thunderstorms. Locally dense fog is possible. Flooding rains may occur west of an Interstate 45 line. Lows 61 Spring to 65 La Marque
Wednesday: Showers and thunderstorms, heavy at times. Flooding is possible; a few thunderstorms may be severe. Highs 67 Jersey Village to 71 League City
Wednesday Night: Showers ending early. Clearing and a bit cooler. Lows 53 Addicks to 57 Webster
Thursday: Partly sunny and mild. Highs 68 Satsuma to 72 Kemah
Friday: Locally dense fog in the morning. Mostly cloudy, breezy with light rain and drizzle likely in the afternoon. High 72, Low 54
Saturday: Variable cloudiness, warmer and more humid with showers and thunderstorms likely, mostly north of Interstate 10 before sunset. Heavy showers and thunderstorms widespread on Saturday night. High 75, Low 62
Sunday: Heavy rain and thunderstorms during the morning. Rain ending, mostly cloudy, breezy and much colder in the afternoon. A.M. High 74, Sunday night low 42.